/* Copyright (C) 2014 Daniel Dressler and contributors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License. */

#define _GNU_SOURCE

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include <ifaddrs.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <net/if.h>

#include <fcntl.h>
#include <unistd.h>
#include <errno.h>

#include "options.h"
#include "logging.h"
#include "tcp.h"


struct tcp_sock_t *tcp_open(uint16_t port, char *interface) {
    struct tcp_sock_t *this = calloc(1, sizeof *this);
    if (this == NULL) {
        ERR("IPv4: callocing this failed");
        goto error;
    }

    /* Open [S]ocket [D]escriptor */
    this->sd = -1;
    this->sd = socket(AF_INET, SOCK_STREAM, 0);
    if (this->sd < 0) {
        ERR("IPv4 socket open failed");
        goto error;
    }
    /* Set SO_REUSEADDR option to allow for a clean host/port unbinding even with
       pending requests on shutdown of ippusbxd. Otherwise the port will stay
       unavailable for a certain kernel-defined timeout. See also
       http://stackoverflow.com/questions/10619952/how-to-completely-destroy-a-socket-connection-in-c */
    int true = 1;
    if (setsockopt(this->sd, SOL_SOCKET, SO_REUSEADDR, &true, sizeof(int)) == -1) {
        ERR("IPv4 setting socket options failed");
        goto error;
    }

    /* Find the IP address for the selected interface */
    struct ifaddrs *ifaddr, *ifa;
    getifaddrs(&ifaddr);
    for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) {
        if (ifa->ifa_addr == NULL)
            continue;
        if ((strcmp(ifa->ifa_name, interface) == 0) &&
            (ifa->ifa_addr->sa_family == AF_INET))
            break;
    }
    if (ifa == NULL) {
        ERR("Interface %s does not exist or IPv4 IP not found.", interface);
        goto error;
    }

    /* Configure socket params */
    struct sockaddr_in addr, *if_addr;
    if_addr = (struct sockaddr_in *) ifa->ifa_addr;
    memset(&addr, 0, sizeof addr);
    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);
    addr.sin_addr.s_addr = if_addr->sin_addr.s_addr;
    /* addr.sin_addr.s_addr = htonl(0xC0A8000F); */
    NOTE("IPv4: Binding to %s:%d", inet_ntoa(if_addr->sin_addr), port);

    /* Bind to the interface/IP/port */
    if (bind(this->sd,
             (struct sockaddr *) &addr,
             sizeof addr) < 0) {
        if (g_options.only_desired_port == 1)
            ERR("IPv4 bind on port failed. "
                "Requested port may be taken or require root permissions.");
        goto error;
    }

    /* Let kernel over-accept max number of connections */
    if (listen(this->sd, HTTP_MAX_PENDING_CONNS) < 0) {
        ERR("IPv4 listen failed on socket");
        goto error;
    }

    return this;

    error:
    if (this != NULL) {
        if (this->sd != -1) {
            close(this->sd);
        }
        free(this);
    }
    return NULL;
}

struct tcp_sock_t *tcp6_open(uint16_t port, char *interface) {
    struct tcp_sock_t *this = calloc(1, sizeof *this);
    if (this == NULL) {
        ERR("IPv6: callocing this failed");
        goto error;
    }

    /* Open [S]ocket [D]escriptor */
    this->sd = -1;
    this->sd = socket(AF_INET6, SOCK_STREAM, 0);
    if (this->sd < 0) {
        ERR("Ipv6 socket open failed");
        goto error;
    }
    /* Set SO_REUSEADDR option to allow for a clean host/port unbinding even with
       pending requests on shutdown of ippusbxd. Otherwise the port will stay
       unavailable for a certain kernel-defined timeout. See also
       http://stackoverflow.com/questions/10619952/how-to-completely-destroy-a-socket-connection-in-c */
    int true = 1;
    if (setsockopt(this->sd, SOL_SOCKET, SO_REUSEADDR, &true, sizeof(int)) == -1) {
        ERR("IPv6 setting socket options failed");
        goto error;
    }

    /* Find the IP address for the selected interface */
    struct ifaddrs *ifaddr, *ifa;
    getifaddrs(&ifaddr);
    for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) {
        if (ifa->ifa_addr == NULL)
            continue;
        if ((strcmp(ifa->ifa_name, interface) == 0) &&
            (ifa->ifa_addr->sa_family == AF_INET6))
            break;
    }
    if (ifa == NULL) {
        ERR("Interface %s does not exist or IPv6 IP not found.", interface);
        goto error;
    }

    /* Configure socket params */
    struct sockaddr_in6 addr, *if_addr;
    char buf[64];
    if_addr = (struct sockaddr_in6 *) ifa->ifa_addr;
    memset(&addr, 0, sizeof addr);
    addr.sin6_family = AF_INET6;
    addr.sin6_port = htons(port);
    addr.sin6_addr = if_addr->sin6_addr;
    addr.sin6_scope_id = if_nametoindex(interface);
    if (inet_ntop(addr.sin6_family, (void *) &(addr.sin6_addr),
                  buf, sizeof(buf)) == NULL) {
        ERR("Could not determine IPv6 IP address for interface %s.",
            interface);
        goto error;
    }
    NOTE("IPv6: Binding to [%s]:%d", buf, port);

    /* Bind to the interface/IP/port */
    if (bind(this->sd,
             (struct sockaddr *) &addr,
             sizeof addr) < 0) {
        if (g_options.only_desired_port == 1)
            ERR("IPv6 bind on port failed. "
                "Requested port may be taken or require root permissions.");
        goto error;
    }

    /* Let kernel over-accept max number of connections */
    if (listen(this->sd, HTTP_MAX_PENDING_CONNS) < 0) {
        ERR("IPv6 listen failed on socket");
        goto error;
    }

    return this;

    error:
    if (this != NULL) {
        if (this->sd != -1) {
            close(this->sd);
        }
        free(this);
    }
    return NULL;
}

void tcp_close(struct tcp_sock_t *this) {
    close(this->sd);
    free(this);
}

uint16_t tcp_port_number_get(struct tcp_sock_t *sock) {
    sock->info_size = sizeof sock->info;
    int query_status = getsockname(sock->sd,
                                   (struct sockaddr *) &(sock->info),
                                   &(sock->info_size));
    if (query_status == -1) {
        ERR("query on socket port number failed");
        goto error;
    }

    return ntohs(sock->info.sin6_port);

    error:
    return 0;
}

struct http_packet_t *tcp_packet_get(struct tcp_conn_t *tcp,
                                     struct http_message_t *msg) {
    /* Alloc packet ==---------------------------------------------------== */
    struct http_packet_t *pkt = packet_new(msg);
    if (pkt == NULL) {
        ERR("failed to create packet for incoming tcp message");
        goto error;
    }

    size_t want_size = packet_pending_bytes(pkt);
    if (want_size == 0) {
        NOTE("TCP: Got %lu from spare buffer", pkt->filled_size);
        return pkt;
    }

    struct timeval tv;
    tv.tv_sec = 3;
    tv.tv_usec = 0;
    setsockopt(tcp->sd, SOL_SOCKET, SO_RCVTIMEO,
               (char *) &tv, sizeof(struct timeval));

    while (want_size != 0 && !msg->is_completed && !g_options.terminate) {
        NOTE("TCP: Getting %d bytes", want_size);
        uint8_t *subbuffer = pkt->buffer + pkt->filled_size;
        ssize_t gotten_size = recv(tcp->sd, subbuffer, want_size, 0);
        if (gotten_size < 0) {
            int errno_saved = errno;
            ERR("recv failed with err %d:%s", errno_saved,
                strerror(errno_saved));
            tcp->is_closed = 1;
            goto error;
        }
        NOTE("TCP: Got %d bytes", gotten_size);
        if (gotten_size == 0) {
            tcp->is_closed = 1;
            if (pkt->filled_size == 0) {
                /* Client closed TCP conn */
                goto error;
            } else {
                break;
            }
        }

        packet_mark_received(pkt, (unsigned) gotten_size);
        want_size = packet_pending_bytes(pkt);
        NOTE("TCP: Want more %d bytes; Message %scompleted", want_size,
             msg->is_completed ? "" : "not ");
    }

    NOTE("TCP: Received %lu bytes", pkt->filled_size);
    return pkt;

    error:
    if (pkt != NULL)
        packet_free(pkt);
    return NULL;
}

int tcp_packet_send(struct tcp_conn_t *conn, struct http_packet_t *pkt) {
    size_t remaining = pkt->filled_size;
    size_t total = 0;
    while (remaining > 0 && !g_options.terminate) {
        ssize_t sent = send(conn->sd, pkt->buffer + total,
                            remaining, MSG_NOSIGNAL);
        if (sent < 0) {
            if (errno == EPIPE) {
                conn->is_closed = 1;
                return 0;
            }
            ERR("Failed to sent data over TCP");
            return -1;
        }

        size_t sent_ulong = (unsigned) sent;
        total += sent_ulong;
        if (sent_ulong >= remaining)
            remaining = 0;
        else
            remaining -= sent_ulong;
    }
    NOTE("TCP: sent %lu bytes", total);
    return 0;
}


struct tcp_conn_t *tcp_conn_select(struct tcp_sock_t *sock,
                                   struct tcp_sock_t *sock6) {
    struct tcp_conn_t *conn = calloc(1, sizeof *conn);
    if (conn == NULL) {
        ERR("Calloc for connection struct failed");
        goto error;
    }
    fd_set rfds;
    int retval = 0;
    int nfds = 0;
    FD_ZERO(&rfds);
    if (sock) {
        FD_SET(sock->sd, &rfds);
        nfds = sock->sd;
    }
    if (sock6) {
        FD_SET(sock6->sd, &rfds);
        if (sock6->sd > nfds)
            nfds = sock6->sd;
    }
    if (nfds == 0) {
        ERR("No valid TCP socket supplied.");
        goto error;
    }
    nfds += 1;
    retval = select(nfds, &rfds, NULL, NULL, NULL);
    if (g_options.terminate)
        goto error;
    if (retval < 1) {
        ERR("Failed to open tcp connection");
        goto error;
    }
    if (sock && FD_ISSET(sock->sd, &rfds)) {
        conn->sd = accept(sock->sd, NULL, NULL);
        NOTE ("Using IPv4");
    } else if (sock6 && FD_ISSET(sock6->sd, &rfds)) {
        conn->sd = accept(sock6->sd, NULL, NULL);
        NOTE ("Using IPv6");
    } else {
        ERR("select failed");
        goto error;
    }
    if (conn->sd < 0) {
        ERR("accept failed");
        goto error;
    }
    return conn;

    error:
    if (conn != NULL)
        free(conn);
    return NULL;
}

void tcp_conn_close(struct tcp_conn_t *conn) {
    /* Unbind host/port cleanly even with pending requests. Otherwise
       the port will stay unavailable for a certain kernel-defined
       timeout. See also
       http://stackoverflow.com/questions/10619952/how-to-completely-destroy-a-socket-connection-in-c */
    shutdown(conn->sd, SHUT_RDWR);

    close(conn->sd);
    free(conn);
}
